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| United States Patent |
5,504,635
|
|
Lee
|
April 2, 1996
|
Device for adjusting a tension arm spring biasing force
Abstract
A video cassette recorder is provided with a device for finely adjusting
the tension of a loaded magnetic tape, which comprises a tension arm
rotatably pivoted at a deck of the recorder and having a tension pole
secured thereto for exerting a pressing force on the tape, a coil spring
fixed to the tension arm for biasing the tension arm to urge the tension
pole against the tape, a slider movably engaged with an elongated slot of
the deck and associated with the coil spring, and an adjusting knob
rotatably mounted to the deck for actuating the slider along the elongated
slot in a lateral direction. The slider includes a rack formed at a side
surface thereof. The adjusting knob includes a pinion provided on a shaft
thereof and meshed with the rack of the slider. With a lateral movement of
the slider caused by the rotation of the adjusting knob, the biasing force
of the coil spring exerted against the tension arm is varied to adjust the
pressing force of the tension pole applied to the tape.
| Inventors:
|
Lee; Chang-Ho (Incheon, KR)
|
| Assignee:
|
Daewoo Electronics Co., Ltd. (Seoul, KR)
|
| Appl. No.:
|
279775 |
| Filed:
|
July 25, 1994 |
Foreign Application Priority Data
| Jul 31, 1993[KR] | 1993-14882 |
| Current U.S. Class: |
360/95; 242/334.6; 360/85 |
| Intern'l Class: |
G11B 015/43 |
| Field of Search: |
360/96.1,96.3,95,85,74.3
242/334,334.6
|
References Cited
U.S. Patent Documents
| 4943874 | Jul., 1990 | Takeda et al. | 360/85.
|
| 5070422 | Dec., 1991 | Sasaki et al. | 360/85.
|
| 5093752 | Mar., 1992 | Sato et al. | 360/85.
|
| 5305162 | Apr., 1994 | Kushiro et al. | 360/85.
|
| Foreign Patent Documents |
| 58-196648 | Nov., 1983 | JP | 242/334.
|
| 60-000642 | Jan., 1985 | JP | 242/334.
|
| 60-223051 | Nov., 1985 | JP | 360/74.
|
| 61-029445 | Feb., 1986 | JP | 360/96.
|
| 3-228244 | Oct., 1991 | JP | 242/334.
|
| 3-252951 | Nov., 1991 | JP | 360/74.
|
Primary Examiner: Levy; Stuart S.
Assistant Examiner: Renner; Craig A.
Attorney, Agent or Firm: Anderson Kill Olick & Oshinsky
Claims
What is claimed is:
1. A device for adjusting the tension of a magnetic tape loaded in a video
cassette recorder, comprising:
a tension arm rotatably pivoted on a deck of the recorder at a first end
portion thereof and having a tension pole secured to a second end portion
thereof for exerting a pressing force on the magnetic tape loaded in the
recorder;
a spring fixed to the first end portion of said tension arm for biasing
said tension arm to urge said tension pole against the magnetic tape;
a slider secured to an end of the spring and tightly fitted into an
elongated slot of the deck for adjusting the biasing force of the spring
by a lateral movement of the slider, said slider including a rack formed
at a side surface thereof;
an adjusting knob rotatably mounted to the deck and having a pinion meshed
with the rack of the slider, wherein said slider is forcibly moved in the
lateral direction along the elongated slot by the rotation of the
adjusting knob to finely control the biasing force of the spring against
the tension arm, adjusting the pressing force of the tension pole applied
to the magnetic tape; and
a series of indication scales formed on a surface of the deck and arranged
adjacent to the elongated slot for indicating various tension levels of
the tape.
2. The tape tension adjusting device of claim 1, wherein said adjusting
knob is separably held in a hole of the deck.
Description
FIELD OF THE INVENTION
The present invention relates to a magnetic tape tension adjusting
mechanism; and, more particularly, to a device for adjusting the tension
of a magnetic tape loaded in a video cassette recorder ("VCR") so as to
maintain the tape in a predetermined contact relationship with a head drum
of the VCR during the running operation of the tape.
DESCRIPTION OF THE PRIOR ART
In general, a videotape loaded in a VCR travels along a given path provided
on a deck of the VCR and comes in contact with a head drum to record video
information thereon or reproduce recorded information therefrom. However,
loosening of the videotape during the operation of the VCR may cause
operational failures, noises and/or distortions as the tape may not
maintain a proper contact with the head drum. Therefore, in order to
prevent such failures, the magnetic tape loaded needs to be maintained in
a proper pressure contact with the head drum. To this end, a reverse force
against the forward running of the tape is provided to maintain the
tension and pressured contact of the tape with the head drum.
A typical tape tension adjusting device for use in a VCR is shown in FIG.
1. The VCR shown therein includes a deck 2, a supply reel base 4 rotatably
mounted on the deck 2, and a head drum 6 rotatably coupled to the deck 2.
A magnetic tape T drawn out of a supply reel 7 of a video cassette loaded
in the VCR runs along an eraser head 8, a guide post 10 and the drum head
6, etc., and then is wound over a take up reel of the cassette (not
shown).
As shown in FIG. 1, disposed between the supply reel base 4 and the head
drum 6 is a tape tension adjusting device 12 which serves to adjust the
tension of the loaded tape T in a required level. The adjusting device 12
comprises a tension arm 14, one end of which is rotatably pivoted at the
deck 2 by a pin 16 and the other end of which includes a tension pole 18
secured thereto for pressing the tape T. In addition, fixed to the one end
of the tension arm 14 is a coil spring 20 which urges the tension arm 14
in a counterclockwise direction about the pin 16, thereby causing the
tension pole 18 to push the tape T. The deck 2 is provided with a
plurality of hooks 22 arranged in a given interval, one of which is
selectively engaged with the coil spring 20.
According to the prior art adjusting device, if it is required to adjust
the tension of the tape T, the engagement of the coil spring 20 with one
of the hooks 22 will cause the tension arm 14 to rotate clockwise or
counterclockwise about the pin 16, increasing or alleviating the tension
force applied to the tape T through the movement of the tension pole 18.
However, this adjusting device has a deficiency in that the interval
arrangement of the hooks 22 on the deck 2 renders it difficult to finely
adjust the tension of the tape or to achieve a precise contact of the tape
with the head drum. Further, repeated separation and engagement between
the coil spring and each one of the hooks is required to adjust the
tension of the tape, which may cause a premature failure of the device.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
adjusting device for use in a VCR, which is capable of finely adjusting
the tension of a magnetic tape loaded in the VCR to maintain a precise
contact of the tape with a head drum of the VCR.
It is another object of the present invention to provide an adjusting
mechanism which is designed to adjust the tension of a loaded magnetic
tape with ease and convenience.
The above and other objects of the present invention are accomplished by
providing a magnetic tape tension adjusting device for a VCR, which
comprises:
a tension arm rotatably pivoted at a deck of the VCR at a first end portion
thereof and having a tension pole secured to a second end portion thereof
for exerting a pressing force on a loaded magnetic tape in the VCR;
means fixed to the first end portion of said tension arm for biasing said
tension arm to urge said tension pole against the magnetic tape;
a slider movably engaged with an elongated slot of the deck and associated
with said biasing means; and
means for actuating said slider along the elongated slot in a lateral
direction to adjust the pressing force of said tension pole applied to the
magnetic tape through a biasing force variation of said biasing means
caused by the movement of the slider.
In accordance with a preferred embodiment of the present invention, the
slider includes a rack formed at a side surface thereof and is tightly
coupled to the elongated slot of the deck to forcibly move in the lateral
direction by the actuating means. Further, the actuating means includes an
adjusting knob rotatably held in a hole of the deck and having a pinion
meshed with the rack of the slider. Therefore, the rotation of the
adjusting knob will cause the slider to properly move along the slot in a
required lateral direction, thereby providing a fine adjustment of the
tension of the tape by the rotating actuation of the tension arm. After
the completion of the tension adjustment of the tape, the adjusting knob
may be removed from the deck in accordance with another embodiment of the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become apparent from the following description of preferred
embodiments given in conjunction with the accompanying drawings, in which:
FIG. 1 is a plan view of a prior art device for adjusting the tension of a
magnetic tape loaded in a VCR;
FIG. 2 is a plan view of a magnetic tape tension adjusting device for a VCR
in accordance with a preferred embodiment of the present invention;
FIG. 3 is a sectional view taken along line A--A of FIG. 2; and
FIG. 4 is a view similar to that of FIG. 3 but illustrates an alternative
tension adjusting mechanism of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 2, there is shown a magnetic tape tension adjusting
device for use in a VCR in accordance with a preferred embodiment of the
present invention. A supply reel base 30 and a head drum 32 are rotatably
mounted on a deck 34 of the VCR in a spaced relationship with each other.
A loaded magnetic tape T travels along a given path provided on the deck
34, i.e., along the path .defined by an eraser head 36, a guide post 38,
the head drum 32 and so forth.
As shown in FIG. 2, the magnetic tape tension adjusting device 40 is
provided at a location between the supply reel base 30 and the head drum
32 so as to adjust the tension of the magnetic tape T loaded therein. The
tension adjusting device 40 comprises a tension arm 42 located at the tape
running path on the deck 34, one end portion 44 of which is rotatably
pivoted at a pin 46 fixed to the deck 34 and the other end portion 48 of
which includes a tension pole 50 secured thereto so as to exert a pressing
force on the magnetic tape T, thereby preventing looseness of the tape. A
coil spring 52 is engaged with the first end portion 44 of the tension arm
42 to bias the tension arm 42 counterclockwise about the pin 46, enabling
the tension pole 50 to press the tape T.
As depicted in FIG. 2, an elongated guide slot 54 is provided at the deck
34 in a lateral direction and spaced from the tension arm 42. A slider 56
is movably engaged with the elongated slot 54 of the deck 34. In addition,
provided on the slider 56 is a hook 58 which is adapted to engage with the
coil spring 52. The slider 56 includes a rack 60 formed at a side portion
thereof.
As best shown in FIG. 3, rotatably mounted to the deck 34 is an adjusting
knob 62 which is adapted to actuate the slider 56 along the elongated slot
54 in the lateral direction. The adjusting knob 62 includes a shaft 64
rotatably held in a hole 66 of the deck 34, and a pinion 68 provided on
the shaft 64 and meshed with the rack 60 of the slider 56. Therefore, the
slider 56 is moved along the elongated slot 54 in the right or left
direction by a clockwise or counterclockwise rotation of the adjusting
knob 62 to adjust the biasing force of the coil spring 52 applied to the
tension arm 42. This causes the tension arm 42 to be rotated clockwise or
counterclockwise about the pin 46 due to a variation in the biasing force
of the coil spring 52, thereby adjusting the pressing force of the tension
pole 50 exerted on the magnetic tape T. As a result, the tension of the
tape T is adjusted in a required level to maintain an accurate contact of
the tape T with the head drum 32 during the running operation of the tape.
In particular, meshing of the pinion 68 of the adjusting knob 62 with the
rack 60 of the slider 56 accomplishes a fine adjustment of the biasing
force of the coil spring 52 against the tension arm 42, maintaining the
required tension of the tape T; and renders it easy to adjust the tension
of the tape.
On the other hand, it is required that the slider 56 remain to be
stationary at a set position of the elongated slot 54 without moving in
any lateral direction after the completion of the tension adjustment of
the tape. To this end, the slider 56 is tightly coupled to the slot 54 of
the deck 34 so that it is forcibly moved in the lateral direction by an
external force, i.e., the rotating force of the adjusting knob 62.
Preferably, the adjusting knob 62 may be separably engaged with the hole
66 of the deck 34 so that it may be removed from the deck 34 after the
tension adjustment of the tape has been finished (see FIG. 3).
Referring back to FIG. 2, formed on a surface of the deck 34 and arranged
adjacent to the slot 54 are a plurality of indication scales 70 which
indicate various tension levels of the tape so as to visibly determine a
required amount of movement of the slider 56, thereby facilitating the
tension adjusting process of the tape. Further, a mark 72 may be
preferably incised at one of the scales 70 in order to establish an
initial setting position of the slider 56 in the slot 54.
FIG. 4 shows an alternative tension adjusting mechanism of the present
invention, which is similar to the one illustrated in FIG. 3 with the
exception of the attachment of the adjusting knob 62 to the deck 34. In
this embodiment, the adjusting knob 62 is undetachably engaged with the
hole 66 of the deck 34 to actuate the slider 56 by its rotation.
Additionally, formed at the top surface of the adjusting knob 62 is a
crossed groove 74 which is adapted to engage with a hand tool, e.g., a
driver (not shown) in the tension adjustment of the tape. Accordingly,
with the rotation of the adjusting knob 62 by the tool, the slider 56 is
moved along the elongated slot 54 in the lateral direction to adjust the
tension of the tape in the above mentioned manner.
Although the invention has been shown and described with respect to the
preferred embodiments, it will be understood by those skilled in the art
that certain changes and modifications may be made without departing from
the spirit and scope of the invention as defined in the following claims.
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